To prevent just one death, researchers found,1,055 men would need to be offered screening and 37 would be diagnosed with cancer and forced to make tough decision about whether or not to undergo treatment.

What's more, only two of the eight countries involved in the study saw fewer prostate cancer deaths, while the others six did not.

Screening is done with a simple blood test that measures levels of prostate-specific antigen, or PSA.

The new findings come just months after a large American study found no benefit of screening men at average risk and are unlikely to quell the current controversy over PSA testing.

Three years ago, doctors with the European Randomized Study of Screening for Prostate Cancer (ERSPC) reported that PSA testing, found 1,410 men would need to be screened to prevent one prostate cancer death.

In the process, 47 men would be diagnosed with cancer, risking side effects from treatment without benefiting.

The new results from the European team extend the follow-up period from the earlier study to 11 years on average for more than 162,000 men ages 55 to 69.

The updated study shows slightly more benefits in terms of cancer deaths than the earlier data.

Dr. Fritz Schroder, who coordinated the study, said he expects future updates to show even bigger differences between screened and unscreened men.

"On the other hand, the main downside is overdiagnosis," Schroder told Reuters Health by email, referring to the dozens of tumors that would be detected by screening, yet would never have become deadly if left alone.

Men with prostate cancer have different treatment options, ranging from a wait-and-see approach to radiation or surgery. The invasive treatments may have complications and often lead to impotence and incontinence.

The new results were published Wednesday in the New England Journal of Medicine. Two of Schroder's co-authors hold a patent for a PSA test, and one is receiving royalties from it.

One in six American men will get prostate cancer during their lifetime, although only a minority of them will die from the disease.

The PSA test is given annually to millions of American men, but more and more experts question whether it's worth the money and the false alarms it triggers in about half the people flagged by the test.

The government-backed U.S. Preventive Services Task Force has proposed a recommendation against prostate cancer screening for men with no symptoms.

Dr. Otis Brawley, chief medical officer of the American Cancer Society, said the European study is actually eight studies in eight countries, and only in Sweden and the Netherlands did PSA testing significantly reduce the risk of death from prostate cancer.

"Screening saves lives if you live in the Netherlands and Sweden, but not the other six places," he told Reuters Health in a telephone interview.

One factor that may have skewed the Swedish data, he said, is that men who were screened were treated at an academic medical center, while men in the control group who developed cancer were treated elsewhere in the community. That alone might account for the lower mortality rate in the PSA population.

In all, there were 299 prostate cancer deaths in the screening group compared to 462 in the control group that was not screened.

Brawley said PSA testing is being widely promoted because "there's a huge profit in screening and treatment" for prostate cancer, even though most studies have failed to show that screening saves lives.

In part because the risk from pursuing false alarms is so high," no professional organization recommends routine screening for people over 50, regardless of family history," he said.

Schroder said guidelines from the National Comprehensive Cancer Network, the European Association of Urology, and American Urological Association "provide a sensible recommendation: men who wish to be examined need to be carefully informed with balanced views and answers to their questions before they take a decision to be screened."

In an editorial, public health expert Dr. Anthony Miller of the University of Toronto, said it would be "unwise" to intensify PSA testing.

"I think it would be advisable to follow the preliminary recommendations of the U.S. Preventive Services Task Force," he wrote.